2.7. Nitric oxide anion scavenging activity

An aliquot 1 mL of extract, Tb-01, and ascorbic acid (0.4 mg/mL, 0.6 mg/mL, 0.8 mg/mL, 1.0 mg/mL, and 1.2 mg/mL in methanol) was mixed in 1 mL of sodium nitroprusside (10 mM) in phosphate buffered saline and incubated at room temperature for 180 minutes. The reaction does not have test sample but equivalent amount of methanol served as control. After the incubation period, 0.5 mL of Greiss reagent (1% sulfanilamide, 2% phosphoric acid, and 0.1% naphthylenediamine dihydrochloride) was added. Ascorbic acid was used as a positive control and absorbance of the chromophore formed was read by a UV spectrophotometer at 546 nm.15